1. Field of the Invention
The present invention relates to liquid treatment equipment for implementing treatment in liquid on a surface of a substrate to treat and a liquid treatment method therefor, and a semiconductor device manufacturing method useful for implementing such liquid treatment and semiconductor device manufacturing equipment useful therefor. In particular, the present invention relates to liquid treatment equipment suitable for implementing smooth and high quality liquid treatment with less manufacturing burden and a liquid treatment method suitable therefor, and a semiconductor device manufacturing method useful in implementing such liquid treatment and semiconductor device manufacturing equipment useful therefor.
2. Description of the Related Art
Recently, a liquid treatment step in a manufacturing process of semiconductor devices or liquid crystal devices, with an increase of demands for finer processing in the manufacture of semiconductor devices or liquid crystal devices, is more and more frequently employed in the place of a reaction process in gaseous phase.
As an example of a liquid treatment step, a step for implementing copper plating on a wafer surface that is a substrate to treat will be explained. Such step for implementing copper plating is in general part of a step of forming a copper pattern in a fine trench or bia hole previously formed at the respective portions on the wafer surface. Each of the portions that are formed in a large number on the wafer surface is an area to be a single semiconductor device (semiconductor chip).
In implementing copper plating on the wafer surface to treat, on the surface, in advance, a conductive seed layer that passes electricity to plating to be formed and a plating solution, being a cathode in electrolytic plating and a seed in plating, is formed.
The seed layer, with a thickness of from approximately several nm to approximately 200 nm, combines a copper layer of the same material with a layer of material that is different from the later plating. When mentioning scale relationship with respect to the fine trench or bia hole formed in advance on the wafer surface, the seed layer is formed so that a surface of a sidewall thereof and a bottom surface thereof are covered. While holding a periphery of the wafer thereon such seed layer is formed, an electric conductor (contact) is effected to come into contact with the seed layer to supply electricity for plating.
The wafer thereto the electricity is supplied is immersed in a plating solution bath (treatment solution bath) for the seed layer to be the cathode. In the plating solution bath, an electrolyte solution including plating materials, an aqueous solution of copper sulfate (CuSO4) for instance, is filled and an anode electrode of copper containing phosphorus for instance is disposed in contact with the aqueous solution of copper sulfate. The plating is formed so that the fine trench or bia hole previously formed on the wafer surface is filled, followed by further covering the wafer surface.
In the plating treatment, in order to fill the fine trenches or bia holes previously formed on the wafer surface without voids and to stimulate the formation of the plating, an additive agent is added to the plating solution. In the additive agent, material for stimulating (brightening) the formation of the plating (material containing sulfur, for instance) and material for repressing (suppressing) the formation of the plating (organic high molecular substance, for instance) are compounded. By the competing action of both materials for and against, high quality and efficient plating is targeted.
That is, in order to plate for a surface having trenches or bia holes to be filled without voids, it is necessary to relatively accelerate a plating reaction of the trenches or bia holes and to relatively decelerate a plating reaction of portions that are not trenches or bia holes. Of components of the additive agent, the material containing sulfur for instance that is a material for accelerating the plating formation is relatively small in particle diameter and enters into trenches or bia holes with ease. On the other hand, the material repressing the plating formation, organic polymer material for instance, is relatively large in particle diameter and enters into the trenches or bia holes with difficulty.
Accordingly, the plating is accelerated of the trenches or bia holes but decelerated of the area other than that. Thereby, the plating can be implemented in the trenches or bia holes without voids, with high quality and with high efficiency as a whole.
As mentioned above, in the liquid treatment, the additive agent plays an important role in the quality and productivity of the liquid treatment. Accordingly, the concentration of the additive in the plating solution is necessary to be always controlled, and the plating solution has to be kept agitating to prevent concentration unevenness in the plating solution from occurring. Though the concentration of the additive agent in the plating solution is measured by the use of CVS (Cyclic Voltametric Stripper), it is insufficient in view of accuracy and furthermore at present it is difficult to implement a real time measurement. (additive agent concentration management burden, agitation burden).
Furthermore, each time as the plating solution is used in the plating treatment, the additive agent is consumed and lost. In the consumption and loss, specifically, there are chemical changes due to the contact with the anode electrode, electrical, natural decomposition or the like. To such consumption and loss of the additive agent, it is possible to keep up with to a certain extent by supplying additional additive agent in the plating solution. However, due to remaining chemical change matter and decomposition products, each time as the additive agent is added, the plating solution deteriorates in its quality. Accordingly, at present, the plating solution, after the use of a certain time period, is discarded as a whole. (consumption burden of the additive agent and plating solution).
In addition, mentioning of the seed layer, copper that is a material thereof is oxidized from a surface with the passage of time. When implementing the plating treatment on the oxidized seed layer, the formed film becomes poor in its plating quality. Accordingly, after the formation of the seed layer, time management is implemented to carry out the next step before the oxidation proceeds. (time management burden).
As explained above, there are various kinds of items forcing burdens on the manufacture in the present technology. However, in order to implement smooth and high quality liquid treatment, the above burdens are accepted as necessity.